1. Field of the Invention
The present invention relates to laser systems for medical treatments and in particular, for laser surgical procedures. More particularly, it relates to optical fiber systems and methods used for the treatment of various medical conditions, including venous insufficiency.
2. State of the Art Disclosure Statement
There are a number of human medical conditions in which it is necessary to apply energy to hollow structures of the body from the inside. One of those conditions is venous insufficiency. The human venous system of the lower limbs consists essentially of the superficial venous system and the deep venous system, both connected by perforating veins. The superficial system comprises the great and the small saphenous veins, while the deep venous system includes the anterior and posterior tibial veins, which converge to form the popliteal vein near the knee. The popliteal vein, in turn, becomes the femoral vein when joined by the small saphenous vein.
The venous system comprises valves that function to achieve unidirectional blood flow back to the heart. Venous valves are bicuspid valves wherein each cusp forms a blood reservoir. The bicuspid venous valves force their free surfaces together under retrograde blood pressure. When properly operating, retrograde blood flow is prevented, allowing only antegrade flow to the heart. A bicuspid valve becomes incompetent when its cusps are unable to seal properly under a retrograde pressure gradient such that retrograde blood flow occurs. When retrograde blood flow occurs, pressure increases in the lower venous sections which can, in turn, dilate veins and lead to additional valvular failure.
Valvular failure, usually referred to as venous insufficiency, is a chronic disease that can lead to skin discoloration, varicose veins, pain, swelling and ulcerations. Varicose veins are blood vessels that have become enlarged and twisted and have progressively lost elasticity in their walls. Due to the widening of the blood vessels, the valves cannot be completely closed and the veins lose their ability to carry blood back to the heart. This leads to an accumulation of blood inside the vessels which can, in turn, further enlarge and twist the veins. Varicose veins usually have a blue or purple color and may protrude in a twisted form above the surface of the skin giving rise to a characteristically unattractive appearance. Varicose veins are commonly formed in the superficial veins of the legs, which are subject to high pressure when standing. Other types of varicose veins include venous lakes, reticular veins and telangiectasias.
There are a number of treatments available for eradicating these types of vascular pathologies. Varicose veins are frequently treated by eliminating the insufficient veins. These treatments force the blood that otherwise would flow through the eliminated vein to flow through the remaining healthy veins. Various methods can be used to eliminate problematic insufficient veins, including surgery, sclerotherapy, electro-cautery, and laser treatments.
Endoluminal laser ablation (“ELA”) is a modern minimally invasive technique that is increasingly preferred over surgery, sclerotherapy and electro-cautery approaches for treatment for varicose veins. This is mainly due to the optimal results with minimum undesired side effects obtained in comparison to other methods used. In a typical prior art ELA procedure, an optical fiber is introduced through an introducer sheath into the vein to be treated. An exemplary prior art ELA procedure includes the following steps: First, a guide wire is inserted into the vein to be treated, preferably with the help of an entry needle. Second, an introducer sheath is introduced over the guide wire and advanced to a treatment site. Then, the guide wire is removed leaving the introducer sheath in place. The optical fiber (coupled to a laser source) is then inserted through the introducer sheath and positioned so that the flat emitting face at the distal tip of the fiber and the sheath are at the same point. Often local anesthesia is then applied to the tissue surrounding the vein to be treated. Prior to lasing, the sheath is pulled back from the flat emitting face a distance sufficient to prevent the emitted laser energy from damaging the sheath. Then, the laser is fired to emit laser energy through the flat emitting face and into the blood and/or vein wall directly in front of the emitting face. While the laser energy is emitted, the laser fiber and introducer sheath are withdrawn together to treat and close a desired length of the vein. The laser energy is absorbed by the blood and/or vein wall tissue and, in turn, thermally damages and causes fibrosis of the vein.
U.S. Pat. No. 6,200,332 to Del Giglio discloses an exemplary prior art device and method for under skin laser treatment with minimal insertions into the area of treatment. Common vascular abnormalities such as capillary disorders, spider nevus, hemangioma, and varicose veins can be selectively eliminated. A needle is inserted into the vascular structure and the targeted abnormalities are subjected to emitted laser radiation. The device allows for orientation and positioning of the laser delivering optical fiber during treatment. Infiltrated anesthesia is generally not necessary. An extension piece maintains the optical fiber in a fixed position relative to, and at a fixed distance from, a hand piece to allow the user to know the extent to which the fiber has been inserted into the vein.
U.S. Pat. No. 6,398,777 to Navarro et al. describes another ELA procedure in which percutaneous access into the vein lumen is obtained using an angiocatheter through which a fiber optic line is introduced. The fiber optic line has a bare, uncoated tip defining a flat radiation emitting face. The '777 patent teaches manually compressing the vein, such as by hand or with a compression bandage, to place the vein wall in contact with the flat emitting face of the fiber tip. The laser energy is delivered in high energy bursts into the portion of the vein wall in contact with the bare fiber tip. The wavelength of the laser energy is in the range from about 532 nm to about 1064 nm and the duration of each burst is about 0.2 seconds to about 10 seconds. Each burst delivers from about 5 watts to about 20 watts of energy into the vein wall. The '777 patent and other prior art ELA procedures teach delivering sufficient energy to insure damage to the entire thickness of the vein wall to ultimately result in fibrosis of the vein wall and occlusion of the greater Saphenous vein.
Consistent with the '777 patent, the prior art teaches applying relatively high energy levels (e.g., ≧80 J/cm) in order to improve the treatment success of ELA of incompetent Saphenous veins. Timperman et al. teach that endovenous laser treatments of the Saphenous vein are particularly successful when doses of more than 80 J/cm are delivered. Timperman et al. collected data regarding the length of treated vein and the total energy delivered on 111 treated veins. The wavelength of laser energy applied was 810 nm or 940 nm. Of the 111 treated veins, 85 remain closed (77.5%) during the follow-up period. In this group of successfully treated veins, the average energy delivered was 63.4 J/cm. For the 26 veins in the failure group, the average energy delivered was 46.6 J/cm. No treatment failures were identified in patients who received doses of 80 J/cm or more. P. Timperman, M. Sichlau, R. Ryu, “Greater Energy Delivery Improves Treatment Success Of Endovenous Laser Treatment Of Incompetent Saphenous Veins”, Journal of Vascular and Interventional Radiology, Vol. 15, Issue 10, pp. 1061-1063 (2004).
One drawback associated with this and other prior art ELA treatments is that the laser radiation is applied only through the very small flat emitting face at the bare fiber tip. As a result, substantially only a very small, localized portion of the blood and/or vein wall in front of the flat emitting face directly receives the emitted laser energy at any one time. Yet another drawback of such prior art ELA devices and methods is that the laser radiation is directed only in a forward direction out of the flat emitting face of the fiber. Accordingly, substantially no radiation is emitted radially or laterally from the fiber tip thereby delivering the laser radiation in a relatively localized manner. A further drawback is that the relatively high levels of energy delivered into the vein create significantly increased temperatures which can, in turn, give rise to corresponding levels of pain in the surrounding tissues. The relatively high levels of energy delivered also can give rise to corresponding levels of thermal damage in surrounding tissues. The more intense the thermal damage, the greater is the chance for post procedure pain, bruising and the possibility of paresthesia. Paresthesia is an abnormal and/or unpleasant sensation resulting from nerve injury. Yet another drawback is that such relatively high levels of energy delivery and/or localized concentrations of laser radiation can give rise to vein perforations. As a consequence, such prior art ELA procedures can require relatively high levels of anesthetic, such a local tumescent anesthesia, more time, and can give rise to more stress to both a patient and physician, than otherwise desired. Lower levels of energy can be applied in some cases, if the pullback speed is considerably decreased. However, lowering the speed may still not be enough to cause appropriate vein closure. Furthermore, this would lengthen treatment time considerably and physicians and patients demand progressively shorter treatment times.
A further drawback of prior art ELA treatments is that they employ a tumescent technique involving substantial volumes of anesthesia to create tumescence. For example, a typical prior art ELA treatment, reportedly, employs at least about 100 ml to about 300 ml or more of anesthesia depending on the length of vein to be treated. The anesthesia is injected into the tissue along the length of the vein. In most cases, the anesthesia is injected into a perivenous cavity defined by one or more fascial sheaths surrounding the vein, which requires less volume to create tumescence. In other cases, the anesthesia is injected into the leg tissue surrounding the vein. The anesthesia typically consists essentially of dilute concentrations of Lidocaine and Epinephrine, a vascular restrictor, in a saline solution. One drawback of such techniques is that the anesthetic is toxic, and in some cases when, for example, substantial volumes are employed, the anesthetic can cause adverse patient reactions, such as convulsions. Yet another drawback of the tumescent technique is that patients can experience an undesirable elevation in blood pressure due to the use of Epinephrine. A still further drawback of the tumescent technique is that it requires the injection of substantial volumes of liquid anesthetic along the length of the vein, which adds a significant amount of time to the overall ELA procedure, and can give rise to adverse post treatment side effects, such as black and blue marks, and other adverse effects associated with such large volumes of anesthetic.
Although the tumescent anesthesia or cold saline tumescent infusion used in the tumescent technique of prior art ELA procedures creates a heat sink surrounding the vein, it can still allow for significantly higher levels of thermal damage to the surrounding tissues than desired. The more intense the thermal damage the greater is the chance for post procedure pain, bruising, and the possibility of paresthesia. For example, the significant quantities of tumescent anesthesia employed in prior art ELA procedures typically will prevent a patient from feeling any thermal stimulation of the nerves, and therefore will prevent the patient from alerting the physician to stop or adjust the procedure to prevent undesirable thermal damage. The tibial nerve (TN) and its common peroneal nerve (CPN) branch both are subject to the possibility of such damage. The CPN is very superficial in the lateral leg just below the knee, and thermal damage to this nerve can lead to foot drop. Similarly, the TN is subject to the possibility of thermal damage when exploring high in the popliteal fossa. Depending on its extent, thermal damage to the TN can lead to muscle dysfunction of the calf and foot muscles. The sural nerve (SUN) and Saphenous nerve (SAN) likewise are subject to the possibility of thermal damage when performing ELA of the small Saphenous vein (SSV) or the GSV below the knee. The SUN runs very close to the SSV especially distally closer to the ankle. The SAN runs very close to the GSV below the knee especially, again, distally closer to the ankle. Significant quantities of anesthesia, such as tumescent anesthesia, can unknowingly lead to thermal damage of such nerves.
US Patent Application Publication 2007/0167937 by Brown discloses an apparatus for endovascular techniques for delivering energy to tissue adapted to minimize burn back caused by contact between the apparatus and bodily fluids. Configurations of apparatus include a tip that can be arranged to direct light in a radial direction along an arc extending up to 360 degrees around the fiber.
Mentioned prior art inventions lack the possibility of irradiating a vessel in radial form 360° at multiple emission sections. Physicians and patients prefer short effective treatments with the need for minimum or no anesthesia. Physicians have also expressed the desire for a treatment using minimum energy levels so fiber that has minimum or no chance of being damaged inside treated vessel. There is thus a need for a laser treatment system that improves on the state of the art by providing a better, safe, more robust fiber tool to enhance speed of removal, ease of handling, and eliminate the need for using anesthesia while maintaining the benefits of effective vessel ablation. Present invention addresses this need.